You can’t really define this as the default value, since the default value is evaluated when the method is defined which is before any instances exist. The usual pattern is to do something like this instead: class C: def __init__(self, format): self.format = format def process(self, formatting=None): if formatting is None: formatting = self.format print(formatting) … Read more
Instance variable is the variable declared inside a class, but outside a method: something like: class IronMan { /** These are all instance variables **/ public String realName; public String[] superPowers; public int age; /** Getters and setters here **/ } Now this IronMan Class can be instantiated in another class to use these variables. … Read more
Like most things in Ruby, instance variables aren’t truly “private” and can be accessed by anyone with d.instance_variable_get :@x. Unlike in Java/C++, though, instance variables in Ruby are always private. They are never part of the public API like methods are, since they can only be accessed with that verbose getter. So if there’s any … Read more
You can use the @private keyword inside the {} to make all subsequent variable declarations private. The default visibility is @protected (which is similar to protected in Java) and that generally works well. You’d have to specifically declare a variable as @public for it to be directly accessible outside the class. This Apple documentation has … Read more
In the iPhone world, there’s no garbage collector available. You’ll have to carefully manage memory with reference counting. With that in mind, consider the difference between: name = @”Test”; and self.name = @”Test”; // which is equivalent to: [self setName: @”Test”]; If you directly set the instance variable, without prior consideration, you’ll lose the reference … Read more
It’s not really necessary to declare properties for all ivars. A few points come to mind: If an ivar is only going to be assigned to once during the lifetime of the object, you don’t really gain anything by declaring a property. Just retain/copy/assign during init and then release as necessary during dealloc. If an … Read more
In object-oriented programming it’s up to the developer to ensure an object is always in a consistent state after instantiation and after a method finishes. Other than that you’re free to develop the class as you wish (keeping in mind certain principles with subclassing / overriding and so on). A tool such as Pylint will … Read more
Instance variables in ruby may be a bit confusing when first learning Ruby, especially if you are accustomed to another OO language like Java. You cannot simply declare an instance variable. One of the most important things to know about instance variables in ruby, apart from the notation with an @ sign prefix, is that … Read more
The reason instance variables work on classes in Ruby is that Ruby classes are instances themselves (instances of class Class). Try it for yourself by inspecting DummyClass.class. There are no “static methods” in the C# sense in Ruby because every method is defined on (or inherited into) some instance and invoked on some instance. Accordingly, … Read more
class Foo (object): # ^class name #^ inherits from object bar = “Bar” #Class attribute. def __init__(self): # #^ The first variable is the class instance in methods. # # This is called “self” by convention, but could be any name you want. #^ double underscore (dunder) methods are usually special. This one # gets … Read more